What is in coal ash and the wastewater discharge?

During the last five years the following parameters have been monitored by the Dan River facility in association with their federal discharge permit: Arsenic, Selenium, Copper, Iron, Sulfate, temperature, pH, Total Suspended Solids, oil and grease and nutrients including nitrogen and phosphorus. They have also been required to perform Whole Effluent Toxicity testing – a test that uses the entire waste stream at different concentrations to evaluate its effect on aquatic life.

The wastewater is analyzed, in accordance with EPA guidance, for its potential to be noncompliant with state water quality standards. The analysis of data indicates that the concentration of the compounds monitored at the Dan River facility is significantly lower than what is allowed by EPA. The Dan River facility has also consistently passed all quarterly Whole Effluent Toxicity tests.

Ash has a large variety of constituents, it is mostly consists of silicon oxide, iron oxide, and aluminum oxide. But it also has trace amounts of arsenic, selenium, mercury, boron, thallium, cadmium, chlorides, bromine, magnesium, chromium, copper nickel, and other metals.

The ash composition varies widely depending on the coal type and origin, burning regime, air pollution control equipment, etc.